A discharge lamp used for a projection-type image display device has a problem of reduction in image quality such as a contrast of a projected image caused by deterioration in illuminance due to instability of discharge at startup and long-term use. As a technique pertaining to this, Patent Literature 1 discloses a configuration that detects an arc failure between electrodes of a discharge lamp by a lamp voltage detection circuit (lamp current detection circuit) or an optical sensor to control the lamp. Patent Literature 2 discloses a configuration that detects an illuminating light of a lamp by an optical sensor, notifies a state change in the illuminating light, and adjusts a projected state of an image.